In the case that, for example, a silicon wafer subjected to a photosensitive resin applying step is heated and dried in a process for producing a semiconductor, a heating device called a hot plate is usually used. Conventionally, such a hot plate has a structure a resistance element is arranged on the lower face side of a ceramic substrate. Such a resistance element is formed using, for example, silver paste. Specifically, in the state that a mask for screen printing is set up, silver paste is printed on a substrate through openings in the mask by moving a squeegee in a given direction. After the mask is taken off, the printed paste layer is heated so that a resistance element having a given pattern is baked on the substrate (for example, Japanese Kokai Publication Hei 11-40330 (1999) and so on).
When a hot plate is used, a silicon wafer, which is an object to be heated, is put on the upper surface of the hot plate. By sending an electric current to its resistance element in this state, the resistance element generates heat to heat the whole of the silicon wafer.